Many types of pickups are available for guitars, ranging from coil pickups for metal strings, microphones, and piezo element pickups. Acoustic guitars typically employ a single piezo element installed under the saddle (UST—under saddle transducer). The monophonic signal from this piezo transducer, comprising the summed signals of all 6 strings, is usually run to an on-board (in the guitar) single-channel analog preamp that typically provides a 3-band EQ prior to sending the signal out of the guitar to be plugged into either an acoustic guitar amp or PA system.
While such a system is inexpensive to implement and minimizes the amplified guitar's tendency to produce feedback at high volumes, the resulting sound is generally considered poor due to the response characteristics of the transducer. In particular, because of the direct coupling of the strings to the piezo element through the saddle, the acoustical effects of the guitar body are all but lost. The sound is generally characterized as thin, brittle and “quacky”, and does not compare favorably with the natural sound of a full body acoustic guitar.
Further, guitar players often want to add bass to their sound. One way for a solo performer to do this is to use bass pedals, which greatly complicate the playing. Other methods include devices that will generate bass accompaniment. These can generally be classified into two categories.
The first category are stand-alone octave pedals that accept a mono input from a guitar, and produce a bass (octave shifted) sound from the input. These devices are only musically useful when the performer plays one string at a time. Playing a chord produces an octave double of all the notes and the result is not desirable. They are generally not used with acoustic guitars.
The other category is octave divider algorithms that are integrated into guitar synthesizer systems. These systems can perform per-note octave shifting, but require hex (6-part) pickup systems, specialized connectors and are expensive because of all their other capabilities. Such systems are beyond the budget and requirements of many performers.